| Sogatella furcifera is a serious pest on rice in China. The light-emitting diode (LED) is a kind of semiconductor device that can directly convert electric power into visible light and has many advantages, such as narrow wavelength, long life and low energy consumption, etc. S. furcifera adults display a conspicuous positive phototactic behavior to light stimuli. The blue and green lights from LEDs were more attractive to S. Furcifera in the laboratory. In this study, we compared traps with the different LEDs for effectiveness in luring S. Furcifera in paddy fields. In addition, the changes of retinal cells of S. furcifera after stimulus by different LEDs were studied. The purpose of this study was to provide practical and theoretical basis to develope the LED trap at only capturing S. furcifera. The main results were as follows:1. Trapping effect of different LED (blue(455 nm-458 nm), green(515 nm-518 nm) and UV (380 nm-383 nm)) traps on S. furciferais were studied. The species and quantity of insects captured by LEDs and controls (incandescent and Jiaduo frequency trembler grid lamps) were investigated every two days. Overall results showed that more S. Furciferais were attracted to LEDs compared with controls. There were 6 trapping peaks of S. Furciferais. Among the 6 days, blue light was significantly more effective than green light and UV light in trapping S. Furciferais in 3 days. In Another 3 days, the trapping effect of blue light and green light were no significant difference. The number of S. furciferais captured by blue light (500.0 ±12.4) was obviously higher than that by green light (365.3±2.9) and UV (302.50±14.6) throughout the test period2. The structural changes in retinula cells of S. Furcifera after the irradiation of different LEDs (blue, green and UV) were observed, using transmission electron microscopy The ommatidia of S. furcifera has 8 retina cells where the pigment particles were visible. Rhabdom is composed of the specilization of retinula cells. When the cells were dark-adapted, pigment particles were far away from the rhabdom. After dark-adaptation the eye of S. furcifera is in direct line with the light. Exposure time is 3 mins. The pigment particles moved away from its position adjacent to the rhabdom. Using the ratio a/(a+b) to determine the sensitivity of each cell for different LEDs. The distance between pigment particles and rhabdom boundary is a. The distance between rhabdom boundary and rhabdom center is b. The ratio,wihich ranges from 0 to 1, was calculated for each cess. The lower the ratio value, the more sensitive the cell. When the compound was irradiated by blue light, the ratios of cells 1(0.19±0.03) and cell 2 (0.24 ±0.03) were significantly lower than others, indicated that cell 1 and 2 were blue sensitive. When the light was green, the ratios of cell 3 and 5 were obviously lower than others. Similarly, the ratios of cell 6-8 were significantly lower than others when the light was UV. Comprehensive analysis indicated that cell 1 and 2 were the blue recptors, cell 3 and 5 were the green recptors and cell 6-8 were the UV recptors. |
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